Method of heating fluids



Dec 21, 1948. v1-1. R. SWANSON 2,457,096

METHOD OF HEATING FLUIDS Filed March 20, 1945 2 sheets-sheet 1 m/VEA/Tae WIQ/ R 5/4750 ATTORNEY Dec. 21, 1948.

H. R. swANsoN METHOD OF HEATING FLUIDS 2 Sheets-Sheet 2 Filed March 20, 19455 third zone.

Patented Dec. 21, 1948 UNITED STAT ES *OIFF'ICE Harry --R. Swanson, Katonah, N. Y., assignor, by xmesne assignments, to Petra-Chem Process Gompanylncorporated, NewYork; N. Y., a corvporationof Delaware Application March 20, 1943,1Seri'al No. 479,923

2 Claims.

. 51 This invention relates fluids and their mixtures under controlled temperature conditions and refers more partieularly to a method in which separate fluids are initia'lly heated in separate zones and then-simultaneously;

heated in separate'streams'in a third zoneand thereafter being mixed, either .on-discharge from the third zone or prior thereto, in which latter case the mixture is heated before leavingvthe the liquids when mixed isaccomplished by the temperature to which each of 'thefluids isrheated in the initial zones of vheating.

Where two fluids are-to be heated to different temperatures in orderrto :eifect amixtureat a;

desired high temperature or when .it is desired to mix fluids at different high temperatures and subsequently heat the :mixture, it haswbeen found difficult to maintain control over zthe temperatures of the respectivefluids except :bycontrolling the firing rate of the furnaces in which the fluids are heated orsregulating :the I'quantiti'esiof :fluids chargedto the heaters. vIf'quantities are critical to the mixture, variations arexiund'esirable and objectionable. Furthermore, .controllingithe'rates of firing may give amodicumiof satisfaction where temperatures are relatively-low.andr-there is no necessity for heating theifluids laftermixture but at high temperatures any semblance ;of .control over the temperatures-of the individual :fluids. or the mixture soondisappears.

By heating the separatefluids inaseparateiheaters fired separately, then heating both :fluidsfin separate streams simultaneously in: a thirdzone of heating whereapproximately the samexamount of is supplied in proportion-to the-heating surface, control can be accurately maintained over the ultimate or final temperature oflthe'individual fluids before mixtureby the control of the outlet temperatureof theindividual fluids as discharged from the initial .zones of heating.

As an example, in the conversion of light hydrocarbons as 'practicedfby one of the present day methods, a'light'oil such as naphtha, which niay be designated fluid A, .is heated in a first zone to an outlet temperature of from-900 to lOilG" F.,.a second normallygaseous fluid, such as C4- and lighter hydrocarbons, which'may be designated fluid B, .is heated separately in a second zone to atemperature-different-than'that'to which the fluid is heated in the first some. streamsot-fluids A.and=B are then passedin separate streams through a third zone where they The. two

are simultaneously heated by 'a common'lheat I, .source to increase the temperatureof the two' to-a method of heating The control over the temperature oi:

' fluids correspondingly. By controlling the outlet temperature 01? the respective fluids and Bzas I discharged from the first and: second -zones', "their discharge temperature from the third-zone-, where the fluids are combined, can ibe accurately regulated. In thismanner' there is established definite temperatures at which the hydrocarboniiflui'ds :are 1 mixed, therebyobtaining'op'timum conditions =ior reaction. and maximum yields iofldesirediprodu'cts such as'the olefinsior subsequentxalkylation J and C4 hydrocarbons such as but'enesfand ib'ut-a- =\dienes essential to the synthetic rubberiprogram.

Different results. in the character :and yieldswof the products :may be 1 obtained -'by combining it'he :streams before discharge iromtheithird izone of .-:heating, permitting :the ihe'ating :of thevmixture .in zthis fin'al :zone for a "predetermined; eper-led.

, Alsoxconditions may bealteredincluding temperaitures,rpoint of. mixture and other variations, according to *the stocks treated :and :the i'products desired.

1 Inzthe accompanying drawings whi'chaformmart (Of the instant specification and 281116 1170 .cbe'znead ':.prior .to discharge-so that the miXt-u-re i's -'--subjected .toihe'ating in the third zone,

:Eig. i'iiszan .elevational View partly in :section "of .a horizontal lfurn'ace construction corresponding, in sofiarzas the heating cycle is 'conc-zerned, with Figs. .1 andi2. L'Dhe separate fluids arehe'ated in: separately i'fired zones and superheated simultaneouslyinsaithird z'one receiving its heat from a common source of heating; the mixtu'reoft'he :fluids' taking place on discharge from ithe final zone.

Referring to the drawings and particularly adesc'ribing th'e apparatus-as'shown in 'Fig. "1, three separate ifurna'ces are shown having outer casing to which csurround fcylindrical combustion Y chamberefirdby igas' burn'ers diagrammaticallyshown vat la! iiiThe ihe'ater casings are' line'd with svlit'edole are supported by standards from the inlet 20 to the discharge 2I. I discharge pipe 2| the fluid passes through transfer pipe "22 to inlet pipe 23 of heater 0. In av similar manner fluid is charged to heater B I 28 of heater 0.

2 insulation and fire brick shown diagrammatically at I2. The furnace at the left hand side of the figure for convenience is designated by the letter A, the furnace or heater at the right hand side of the figure by the letter B and the central furnace by the letter C. Around the interior of each of the furnaces are arranged a plurality of vertical heat exchange tubes I3 which are connected at the top and bottom by means of return bends and suitable clean-out plugs conveniently arranged to permit cleaning of the separate banks of tubes and removal of the tubes in case repairs are necessary. In so far as the general construction of the heaters is concerned, they are generally identical to the construction de'scr'ibed inu Patent No. 2,276,527, issued March 17, 1942.

Suspended from the upper part of the combustion chamber in each of the heaters A, Band C by means of rods or supporting hangers I4 are conical bafiles or'deflection cones I5 which serve to divert the combustion gases in the upper part of the combustion chambers outwardly,-

thereby increasing the efliciency of the heaters by restricting the combustion gas passageway ;.and concentrating the convection heat upon the upper portion of the tubes. To obtain the maximum advantage of this convection heat in the convection zone, extended surface in the form of longitudinal fins I6 are attached to the surfaces of the tubes in this section. Due to the tem- Deratures involved, the extended surfaces or fins I6 are used only on the furnaces A and B. Due to' the high inlet temperature of furnace C, the fins would be relatively ineffective in removing neat from the exit flue gas. This heat may be conserved, however, by installing an air preheater above the furnace in the path of the flue .gases which preheats the air supplied to the burners. Furthermore, by preheating the air to the burners in this manner, the flame burst temperature is increased, which may be desirable for certain types of operations. The furnaces I! and are sur mounted by a short tapered breaching I8 and chimneys or stacks I9. In each of the heaters the passage of the combustion gases is substantially the same. From the burners the gases rise, heating the surfaces of the tubes arranged around the inside of the combustion chambers. Near the upper part of the heaters the gases are diverted outwardly by the deflection cones. In heaters A and B the gases pass through the annular space between the cylindrical portion of the baflles where the extended surface fin tube sections of the heating tubes are located. After.

passing the baffles the combustion gases pass through the upper part of the furnace through thetapered breechings I8 to stacks I9.

Describing now the manner in which the fluids are heated in the apparatus shown in Fig. 1, a first fluid is supplied to heater A through pipe 20 and is passed through the tubes of the heater From through pipe 25 and after passing through the heating tubes (not shown), is discharged through pipe 26, transfer line 21 and thence to inlet pipe The vertical tubes in heater C may be divided into a plurality of banks but for simplicity here heater C in Fig. 1 is divide'dinto two banks of tubes, a single bank covering one-half of the combustion chamber for. eachfluid. The fluid from A is heated in one of these banks and the fluid from heater B in the other bank. After heating in furnace C the A fluid is discharged through outlet 24 and the B fluid through outlet 29. The two fluids are then combined at a T or manifold connection 30 and the mixture removed through pipe-3,l';- This mixture passes quenched or otherwise treated.

Describing now the developed view shown in Fig, 2, the tube section for heating the first fluid is designated by the letter A and the tubes by nu- I figure, in place of passing the separate fluids in single banks of tubesfthrough heater C, the fluid fromheater A is divided and flows through a plurality of separate banks designated by nu- V merals I31) and i3c. The fluid from heater B,

instead of flowing through a single bank-of tubes as described and shown in Fig. '1, is in this figure passed through heater C in a plurality of banks of tubes, namely, tubes designated by the numerals I3d and I3e. In other words, the first fluid is charged to the tubes in heater .A through pipe 20 and after passing through tubes I 3'is discharged through pipe 2I, after which it passes through transfer pipe 22 and is introduced to banks of heating tubes I32) and I30 through inlet manifold 23. A second fluid charged to heater B is introduced through pipe 25 and after passing through tubes I3a is discharged through line 26 and passes through transfer pipe 2! to be introduced into the banksof heating tubes I3d and I3e through inlet manifold 28. The separate fluids'are combined on discharge from the heater C at T connections 30 and pass out through pipe 3| as described in Fig. 1.

Fig. 3, as suggested in the description of the figure, shows only heater C with the corresponding tube banks I31), I30, I3d and I3e," as shown in Fig. 2. In this figure, however, in place of combining thesuperheated fluids on their discharge from heater'C, the fluids are combined within the heater itself at connections designated by the numerals 32 and the mixture is thereafter heated in separate -tubes or bank of tubes, diagrammatically shown at 33, after which the heated mixture is discharged through pipe 34,

I This arrangement, after effecting a union of the fluids within'the'heater, provides a means for heating the mixture to any desired degree subsequentto their combination.

In Fig. 4 is shown a horizontal type furnace, as distinguished from the vertical heaters shown at Fig. 1, consisting of vertical walls 35 surmounted by a top' 36 built of brick and properly insulated and lined with suitable refractories. The furnace is divided into separate heating chambers A, B, and 0, corresponding to the separate heaters shown in Fig. 1 by means of baflle walls 31. Combustion gases are supplied to the separate chambers by means of burners II. chambers A, B, and C are open at the top so that the combustion gases pass off to a breeching I8 and out through a chimney I9. As in Fig. 1, the first fluid is introduced through pipe 20 and is circulated through a plurality of horizontal tubes I3 arranged around the interior of combustion chamber A. A second fluid is introduced The separate through pipe 25 and is passed through tubes l3a horizontally positioned upon the walls of combustion chamber B. The first fluid passes through transfer pipe 22 and flows through chamber C through horizontal tubes l3b while the second fluid passes over baffle wall 31 through transfer line 2'! and is circulated through tubes l3d in chamber C. The two separate fluids, after receiving heat from a common source H in chamber C, are combined at T connection 30 and flow out through pipe 31. Although we have shown tubes 13b and I30 equal in number and size to tubes 13d and I3e,'it may be desirable to vary the number of tubes in each bank with respect to each other to obtain the desired heat distribution and desired resultant temperatures.

In Fig. 4 no provision is made for combining the two fluids in the heater C and heating the mixture before discharge although this method of operation is contemplated. The significance of Fig. 4 is to show that the method is not limited to the use of vertical heaters as shown in Fig. 1 but may as well be used in a horizontal type heater more conventional to the art.

By the method of heating two separate fluids, as described in the four figures, fluids of diiferent types can be preheated in separate units or tube banks to a desired degree and thereafter simultaneously heated in a third heater where the fluids are superheated to the extent necessary and thereafter combined prior to discharge from the third heater or upon discharge from the third heater. By an arrangement of this kind the temperature of the individual fluids at the point of mixing can be accurately controlled and this is done by controlling the outlet temperatures of the fluids as they are discharged from the initial zones of heating or preheating stages. To be more explicit, and as an example of the control obtained over the exit temperatures from heater C, fluids of different character may be initially heated in heaters A and B to 950 F.

In heater C the fluid streams A and B are subjected to additional heating suiflcient to raise steam A to a discharge temperature of 1350 F. and stream B to a discharge temperature of 1500 F. By controlling the exit temperatures of the streams as they are discharged from heaters A and B, an accurate control may be maintained upon the respective discharge temperatures of the two streams from heater C.

The above control enables me to obtain a wide range of flexibility in the amounts of the respective fluids and the temperatures to which the respective fluids are heated, important in obtaining optimum operating conditions.

It will be understood that certain feature and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of my claims. obvious that various changes may be made in de tails within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specific details shown and described.

Having thus described my invention, I claim:

1. In the conversion of light hydrocarbons, the steps of heating a light oil in a first zone to a predetermined outlet temperature, heating separately in a second zone a normally gaseous fluid to a temperature different from that to which the fluid is heated in said first zone, then passing streams from said first and second zones separately into a third zone where the temperatures of the two streams are increased by a common heat source, combining said streams in the third zone and regulating the discharge temperature from said third zone by independently controlling the temperatures of the fluids passing from said first and second zones into said third zone.

2. In the conversion of unlike hydrocarbon fluids, the steps of heating one of the fluids in. a first zone to a predetermined outlet temperature, heating separately in a second zone the other fluid to a temperature different from that to which the fluid is heated in said first zone, then passing streams from said first and second zones separately into a third zone where the temperature-s of the two streams are increased by a common heat source, combining said streams in the third zone and regulating the discharge temperature from said third zone by independently controlling the temperatures of the fluids passing from said first and second zones into said third zone.

HARRY R. SWANSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 942,797 Sneddon Dec. 7, 1909 1,706,396 Black Mar. 26, 1929 2,066,808 Sullivan Jan. 5, 1937 2,099,919 Arvesen Nov. 23, 1937 2,100,283 Keith NOV. 23, 1937 2,125,233 Sullivan July 26, 1938 2,192,238 Ocon Mar. 5, 1940 2,212,526 Mekler Aug. 27, 1940 It is further Certificate of Correction Patent No. 2,457,096. December 21, 1948. HARRY R. SWANSON It is hereby certified that errors appear in the printed spec'fication of the above numbered patent requiring correction as follows:

Column 3, line 35, for the Word neat read heat; column 5, line 45, for steam read stream;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent ()fiice.

Signed and sealed this 3rd day of May, A. D. 1949.

THOMAS F. MURPHY,

Assistant Oommz'ssz'oner of Patents. 

